Process for chemically curling cellulose acetates



United States Patent 3,145,075 PROCESS FOR CHEMICALLY CURLING CELLULOSE ACETATES Paul Ernst and Walter Fischer, Burghausen, Upper Bavaria, Germany, assignors to Wacker-Chemie G.m.b.H., Munich, Germany, a German corporation No Drawing. Filed Nov. 14, 1960, Ser. No. 68,591 Claims priority, application Germany Nov. 17, 1959 4 Claims. (Cl. 8-131) This invention relates to chemically curling cellulose acetate fibers or threads, and it has for its object to provide a novel and improved process for this purpose.

Another object of the invention is to provide a simple and efficient process for chemically curling those cellulose acetate fibers and threads which cannot be curled satisfactorily, if at all, by prior art methods of chemical treatment.

Still another object is to provide a process of the above type for intensively and permanently curling cellulose acetate fibers and threads without impairing the stability of the fibrous materials.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

As is known, synthetic fibrous materials can be curled mechanically as well as chemically. As compared with the mechanical method, the chemical method of curling has the advantage of much better stability and recuperative ability, and also greater irregularity of the location and size of the individual curls. These advantages make processing easier and give more body to the merchandise.

Regenerated cellulose fibers get satisfactory curling when merely treated with hot water. On secondary acetate fibers this prior art process has only limited ap plicability. Furthermore, satisfactory curling can be achieved only on freshly spun fibers which still contain some acetone. On hydrophobic triacetate fibers which are spun from hydrophobic solvents, however, no curling can be achieved with water alone Surprisingly, we have discovered that by treatment with a bath consisting of aqueous solutions or emulsions of hydroxycarboxylic acid esters of aliphatic mono or polylalcohols in concentrations, customary for textile aids, up to 10%, very intensive and permanent curling of cellulose acetate fibers and threads can be achieved without the usual loss of stability of the fiber material.

Our process is particularly suitable for the triacetate fiber for which no satisfactory chemical curling process is known as yet. The losses of hydrocarboxylic acid esters are so small that a separate recovery process is unnecessary.

The curling can be effected while in flock, during preparation, or continuously at a suitable stage of the fiber manufacture, for instance in the wet spinning process, immediately after cable wash on the slack cable.

In carrying out the process of the invention, glycolic acid esters of aliphatic monoor poly-acohols, and particularly the glycolic acid butyl ester, are especially advantageous, where its relatively good solubility in water, 7.1% at C., makes it possible to use it without the addition of an emulsifier.

Example 1 1 part by weight of air-dried non-curled cellulose triacetate fibers of 2 den. is immersed in a vat containing 48.5 parts by weight of water and 1.5 by weight of glycolic acid butyl ester, and kept in moderate motion in there for 15 minutes at 90 C. Subsequently the liquid is separated by centrifuge, the fibers washed twice in warm water, scrooped or wrung out and dried at 80 C.

3,145,075 Patented Aug. 18, 1964 The material obtained by this method is well curled and can easily be processed on the teazel.

Example 2 1 part by weight of dry-spun secondary cellulose acetate fibers of 4 den., staple 120 mm. is placed in an emulsion of 3 parts by Weight of glycolic acid hexyl ester, 0.03 parts by weight of emulsifier and 57 parts by weight of water and left there for 5 minutes at 95 C. under slight motion. Further treatment is done as in Example 1. The fiber is processed according to the worsted yarn method. The character of the thread obtained thereby has a much fuller and more wool-like character than usual. Spools of threads weighing 100 g. with this material have a diameter about 20% larger than spools with normally curled fibers.

Example 3 A triacetate cable with 5,000 threads of 2 den. is continuously freed in several stages of its precipitating bath residue and thereafter it is put slack into a J-box from which the cable is pulled out downward after having been there for about 5 minutes. The contents of the J-box is a mixture of 2.5 parts by weight of ,B-oxybutyric acid methyl ester and 97.5 parts by weight water, which is kept at a temperature of C. The cable is wrung out to about 80% moisture, cut in moist condition and dried in the flock. The result is a fiber which is largely similar to the one described in Example 1.

Example 4 1 part by weight of triace-tate fiber of 3 den. is put, without previous drying, still wet, into a bath consisting of 2.5 parts by weight ethylene glycol monoglycolic acid ester 0.75 part by weight antistatic 0.5 part by Weight of a sulphonated tallow 50 parts by weight water and kept at boiling temperature for 30 minutes. The fiber is then centrifuged down to a moisture content of 30% and dried at 80 C. The material can be processed on the teazel very easily and exhibits a curling similar to wool.

Example 5 1 part by weight of a triacetate fiber of 2 den., manufactured by a wet spinning process, is put into a bath consisting of the following:

1.2 parts by weight lactic acid isopropyl ester 0.12 part by weight of a neutral wetting agent, e.g., alkyl polyglycol ether 38.7 parts by weight water The fiber is agitated moderately in this bath for 15 minutes at C. After subsequent pressing the result is a material which gives an excellent fleece when carded.

Example 6 1 part by weight of a dry-spun 4-den. triacetate fiber is treated in accordance with Example 5. The bath consists of the following: 3.6 parts by weight butanediol mono-lactic acid ester 0.18 part by weight of a neutral wetting agent, e.g., alkyl polyglycol ether 56.2 parts by weight Water The fiber thus treated has somewhat fewer curls, but it can be worked very well on the carding machine. The finished threads have a fullness to the touch.

Example 7 1 part by weight of a non-curled, wet spun triacetate fiber-of 2 den. is treated for minutes at boiling temperature with 1.2 parts by weight of aroxyisobutyric acid methyl ester dissolved in 18.8 parts by Weight of Water. The subsequently scrooped and dried fiber has good adhesion and can easily be processed on the teazel.

Example 8 1 part by weight of the fiber material mentioned in Example 7 is put into a bath consisting of 2.1 parts by weight hydracrylic acid isopropyl ester,

and 27.9 parts by weight water and kept in moderate motion in there for minutes at a bath temperature of 95 C. The fiber curled by this method can easily be processed on the textile machines normally used.

While certain specific examples have been given herein for purposes of illustration, it will be evident to those skilled in the art that the invention is capable of various modifications and adaptations Within the scope of the appended claims.

The invention claimed is:

1. Process for chemically curling cellulose acetate fibers which comprises immersing said fibers in a bath consisting essentially of water and 2-10% of an oxycarboxylic acid ester of an aliphatic alcohol having 1-6 carbon atoms, and heating said bath with said fibers immersed therein to a temperature of 90-100 C.

2. Process according to claim 1, characterized by the fact that said bath comprises Water and 210% of a glycolic acid ester of an aliphatic alcohol having 16 carbon atoms.

3. Process according to claim 1, characterized by the fact that said oxycarboxylic acid ester is selected from the group consisting of glycolic acid butyl ester, glycolic acid hexyl ester, p-oxybutyric acid methyl ester, ethylene glycol monoglycolic acid ester, lactic acid isopropyl ester and butanediolmonolacetate.

4. Process for chemically curling cellulose acetate fibers which comprises immersing said fibers in a bath consisting essentially of water and 2-10% of an ester of an aliphatic oxycarboxylic acid wherein the acid portion contains from one to four carbon atoms, and heating said bath With said fibers immersed therein to a temperature of 100 C.

References Cited in the file of this patent UNITED STATES PATENTS 2,165,506 Platt et al. July 11, 1939 2,243,705 Hill et al. May 27, 1941 2,277,163 Sowter et al. Mar. 24, 1942 2,408,381 Dodge Oct. 1, 1946 2,901,311 Nusslein et a1 Aug. 25, 1959 2,925,641 Evans Feb. 23, 1960 3,022,545 Wylde et al. Feb. 27, 1962 FOREIGN PATENTS 795,821 Great Britain May 28, 1958 

1. PROCESS FOR CHEMICALL CURLING CELLULOSE ACETATE FIBES WHICH COMPRISES IMMERSING SAID FIBERS IN A BATH CONSISTING ESSENTIALLY OF WATER AND 2-10% OF AN OXYCARBOXYLIC ACID ESTER OF AN ALIPHATIC ALCOHOL HAVING 1-6 CARBON ATOMS, AND HEATING SAID BATH WITH SAID FIBES IMMERSED THEREIN TO A TEMPERATURE OF 90-100*C. 